PavelSnej,
<script>
function dateTime(obj) {
var date = new Date();
obj.parentNode.nextSibling.innerHTML = date.getHours()+":"+date.getMinutes();
}
</script>
<table>
<tr><td><input type="button" nmae="date" value="Вставить время" onClick="dateTime(this)"></td><td></td></tr>
</table>